Ponds should be constructed in a sunny area with sufficient sunlight and a stable structure. The pond should have a flat slope, and the ideal size ranges from 3/15 to 1/3 hectare, with a water depth of over 1 meter. A 30–50 cm high anti-escape fence should be installed around the pond. During construction, dig a narrow trench about 30 cm deep around the perimeter, then drive stakes 50–70 cm above the trench every 1–1.5 meters. Cover the trench with plastic film, secure it to the stakes, and fill the trench with soil to bury the bottom edge of the film.
Next, after filling the pond with water, plant aquatic vegetation to create a natural habitat for crabs. Before planting, clear the pond and introduce fresh water. Transplanting plants is essential as they provide shelter, food, and hiding places for crabs, helping them avoid predators. The aquatic plants should be diverse and cover at least one-third of the pond. Suitable species include water hyacinth, duckweed, black grass, and floating plants. Vegetables and water peanuts can also be grown along the edges. Remove any leftover fish promptly to prevent decay and contamination.
Crab seedlings are typically stocked in May each year. It’s important to monitor young crabs carefully, as older crabs may appear during this stage. Proper feeding and management must focus on preventing premature maturation.
Stocking density should be adjusted according to crab size. Initially, 400,000 crabs per 1/15 hectare are recommended, with gradual reductions as they grow. After reaching the IV larval stage, the number should be reduced to around 40,000 per 1/15 hectare.
Maintaining good water quality is crucial. Water should be clean, with a transparency of over 40 cm, pH between 7.5 and 8.5, and dissolved oxygen levels above 4 mg/dm³. If water quality declines, flush the pond or use an aerator to improve conditions.
During summer, keep the water temperature between 18–23°C by using groundwater, cold springs, or reservoir water for regular water changes. Shade the pond during hot periods to prevent overheating.
Feeding should follow the principle of "two fine, middle green." In spring and autumn, feed more concentrated animal-based food, supplemented with vegetables. In summer, green feed should dominate. Avoid overfeeding; allow crabs to eat slightly less than full. Young crabs may stop feeding naturally, so avoid moldy feed.
Moss control is important, as it can harm aquatic plants and degrade water quality. To manage moss, apply proper fertilization and water management. Copper sulfate can be used cautiously, but not before or after molting stages. After treatment, change the water thoroughly. Manually remove moss when the pond dries out and ensure complete removal. Use a sieve net when adding water to prevent moss from entering.
Disease prevention involves maintaining clean water and regular disinfection. Lime can be sprinkled once every 10–15 days, using 20 kg per 1/15 hectare. This helps sterilize the water and maintain balance. Minimize the use of medications that could harm crabs. Always prioritize safe and effective practices.
Intellent Cleanroom Cleaning Robot,Cleanroom Intelligent Cleaning Systems,Automatic Intelligent Cleaning Robot
AUSTAR Goup , https://www.hansencleanroom.com